The effect of thyroid hormones on DNA methylation in rat liver in vivo and in vitro

Abstract: Methylation of rat liver DNA was studied in vivo and in vitro in presence of various content of thyroid hormones. Both administration of triiodothyronine into intact rats and thyroidectomy led to considerable alterations in activity of endogenous DNA-methylases and in content of m5C in DNA although distinct correlation between these two factors was not detected. Alterations in the acceptor activity of endogenous DNA towards bacterial DNA-methylases of thy Mbu type demonstrated the processes occurring in vivo. The methylase probe 5'...GGA...3' proved to be the universal means for testing of all the types of thyroid status involving either free DNA or whole nuclei.